As shown in FIG. 1, a nuclear power station conventionally includes a reactor pressure vessel 10 with various configurations of fuel and reactor internals for producing nuclear power. For example, vessel 10 may include a core shroud 30 surrounding a nuclear fuel core 35 that houses fuel structures, such as fuel assemblies, 40. A top guide 45 and a fuel support 70 may support each fuel assembly 40 in core 35 in specified locations. As shown in FIG. 1, each assembly 40 may occupy a position within a general cylindrical core 35; if each assembly 40 has a similar axial height, positions of assemblies within core 35 may be defined in horizontal and vertical offsets from a center or other reference point in core 35.
An annular downcomer region 25 may be formed between core shroud 30 and vessel 10, through which fluid coolant and moderator flows into the core lower plenum 55. For example, in US Light Water Reactor types, the fluid may be purified water, while in natural uranium type reactors, the fluid may be purified heavy water. In gas-cooled reactors, the fluid coolant may be a gas such as helium, with moderation provided by other structures. The fluid may flow upward from core lower plenum 55 through core 35. After being heated in core 35, the energetic fluid may enter core upper plenum 60 under shroud head 65.
FIG. 2 is an illustration of a portion of fuel core 35 from FIG. 1 showing several fuel assemblies 40 positioned about a control blade 80. During operation, control rod drive 12 (FIG. 1) maneuvers control rod blade 80 to a desired axial position among fuel assemblies 40 to obtain a desired power density. Control rod blade 80 typically has a cross or cruciform traverse cross-section; however, rods and other shapes are known control elements useable in nuclear reactors. Each fuel assembly 40 can include an outer channel 15 that surrounds several fuel rods or other nuclear fuel elements. A handle or bale 85 can interconnect with all components of assembly 40 to allow rigid body handling of assembly 40 with bale 85. Fuel assemblies 40 may extend throughout core 35 (FIG. 1), from a fuel support plate 70 at a bottom of core 35 to bales 85 at a top of core 35. In other locations, such as a spent fuel pool or new fuel loading area, fuel assemblies 40 may be similarly situated, without control elements.
Again in FIG. 1, vessel 10 may be sealed and opened through upper head 95 at flange 90. During plant fabrication and at regular service and/or refueling outages, upper head 95 may be removed and operators and/or equipment can access internals of vessel 10 for various purposes. For example, with access to the reactor internals, some of fuel bundle assemblies 40 may be replaced and/or moved within core 35, and maintenance/installation on other internal and external reactor structures may be performed.
FIG. 3 is an illustration of a related art refueling bridge with mast and grapple useable during outages with access to reactor vessel 10 to perform fuel offloading, reloading, shuffling, and/or maintenance. As shown in FIG. 3, a refueling bridge 1 may be positioned above or about flange 90 when reactor vessel 10 is opened. Bridge 1 may include a trolley 2 capable of rotating and/or laterally moving to any horizontal or vertical position above core 35 (FIG. 1). Trolley 2 may include a refueling mast 3 with hoist box and grapple 4. Hoist box and grapple 4 may be movable horizontally and vertically with trolley 2, such that mast 3 and hoist box and grapple 4 can be positioned above desired fuel assembly positions in core 35 with trolley 2. Hoist box and grapple 4 may axially extend from mast 3, such as through a winch or hydraulic force, to reach axially down to a top of fuel assemblies 40 in core 35 (FIG. 1). Grapple 4 may engage with a fuel assembly 40 via bale 85 or another fuel assembly component to lift, lower, reposition, rotate, or otherwise move assembly 40 to a desired position within core 35 or out of core 35 (FIG. 1). For example, hoist box and grapple 4 may move axially upward or downward with an engaged assembly 40 to remove or install the same within core 35, and/or hoist box and grapple 4 may rotate about an axis or move with trolley 2 to another desired horizontal/vertical core location with assembly 40 for shuffling or removal.
As shown in FIG. 3 a local camera and/or light 5 can be attached to hoist box or grapple 4. Camera and/or light 5 may record and/or illuminate a fuel assembly 40 nearby engaged directly below grapple 4 to permit visual inspection of the fuel assembly below hoist box and grapple 4 during access periods. Camera and/or light 5 may be electrically and/or communicatively connected to a control module or receiver in trolley 2 or to permit inspection or recording of fuel assemblies as they are handled for fuel inspectors.